1. Field of the Invention
The present invention relates to an apparatus of manufacturing a semiconductor device and more particularly, to an apparatus of depositing a thin film.
2. Discussion of the Related Art
Due to a method of depositing a thin film such as a chemical vapor deposition (CVD) method with a development of a new material, semiconductor devices such as a large-scale integrated circuit (LSI) or an ultra large-scale integrated circuit (ULSI) are made possible.
The semiconductor devices are generally fabricated by repeating processes of depositing and patterning. These processes are accomplished in a manufacturing apparatus of the semiconductor device under vacuum condition.
The manufacturing apparatus of the semiconductor device is variously classified according to a purpose. In general, the apparatus includes a processing chamber, a controller which controls surroundings within the chamber, and a gas supplying system which stores source materials and provides the source materials.
Recently, for the sake of manufacturing a large capacitive Dynamic Random Access Memory (DRAM) over 1 Gb (gigabit), ABO3 type doubleoxide having a relative dielectric constant of over 100, i.e. perovskite type doubleoxide such as barium-strontium-titanate (BST: (Ba, Sr)TiO3), or tantalum oxide (Ta2O5) is used as a dielectric material of a capacitor. Besides, ruthenium (Ru) has been developed as an electrode material of the capacitor.
The above materials are deposited in the form of a thin film by using an apparatus such as a CVD system, which is the apparatus for processing a single substrate and may be a vertical furnace type.
FIG. 1 shows a related art apparatus of manufacturing a semiconductor device, particularly depositing a thin film. In FIG. 1, the related art apparatus includes a chamber 10, a source supplying system 20 for providing a source material, and a reactive gas supplying system 30 for providing a reactive gas.
The chamber 10 that is an airtight reaction container has an outlet 14 at one side, and the upper part of the chamber 10 is dome-shaped. The air in the chamber 10 is exhausted out of the chamber 10 through the outlet 14. A susceptor 12 is also situated within the chamber 10 and a substrate 1 such as a silicon wafer or a glass substrate is posited on the susceptor 12. The susceptor 12 has a heater (not shown) for applying heat to the substrate 1 in order to improve a reaction rate. Accordingly, by heating the substrate 1, a processing speed gets fast and the gained results become stable.
The source supplying system 20 includes a source material container 22, a liquid mass flow controller (LMFC) 24, a vaporizer 26, and a source gas injector 28. The source material container 22 has a store of a source material in liquid phase. The LMFC 24 controls the flow rate of the source material, and the vaporizer 26 changes the source material going through the LMFC 24 from liquid phase into gas phase. The source gas injector 28 injects a gas phase source material, i.e. a source gas, into the chamber 10 and one end of the source gas injector 28 projects into the chamber 10 passing through the bottom of the chamber 10.
Meanwhile, the reactive gas supplying system 30 is composed of a reactive gas container (not shown), which is situated outside of the chamber 10, and a reactive gas injector 34. The reactive gas within the reactive gas container is injected into the chamber 10 through the reactive gas injector 34.
In the related art apparatus of FIG. 1, first the substrate 1 is loaded on the susceptor 12, and the air within the chamber 10 is exhausted through the outlet 14 by a pumping system (not shown). Therefore, the inside of the chamber 10 forms a vacuum. Next, the source material within the source material container 22 is supplied to the vaporizer 26 after controlling the flow rate via the LMFC 24. The source material, which is liquid phase yet, changes into gas phase in the vaporizer 26, and the gas phase source material, i.e. a source gas, is injected into the chamber 10 through the source gas injector 28. On the other hand, the reactive gas within the reactive gas container (not shown) is simultaneously injected into the chamber 10 through the reactive gas injector 34. At this time, the injected source gas and the injected reactive gas come to diffuse in the inside of the chamber 10 because the inside pressure of the chamber 10 is lower than those of the source gas injector 28 and the reactive gas injector 34. Then, the injected source gas and the injected reactive gas react with each other, and products are created. The products are deposited on the substrate 1, thereby a thin film is formed on the substrate 1. Here, the substrate 1 is heated during the above process.
At this time, radio frequency (RF) power is applied so as to improve more the reaction rate.
Since it treats a single substrate at one time, the related art apparatus of FIG. 1 is high reliable. The source gas and the reactive gas are injected by the source gas injector 28 and the reactive gas injector 34, respectively, so that it is efficient to use the inner space of the chamber 10 and it is easy to control surroundings of the process. Additionally, a superior thin film can be formed because the related art apparatus use a decomposed source gas.
By the way, in the related art apparatus, it is difficult to control the amount of the source gas because of one source gas injector 28 and one vaporizer 26. That is, as there is a limit to the amount of the source gas that the vaporizer 26 can vaporize in an hour and the vaporization rate of a normal source material is relatively low, the amount of the source gas injected into the chamber 10 is very little. If the amount of the source material is increased in order to raise the injection pressure, the vaporization rate of the source material becomes lower and finally the little amount of the source gas is injected into the chamber 10. On the other side, if the amount of the source material is decreased to lower the injection pressure, the gas phase source material is not diffused uniform. Therefore, deposition rate and uniformity of a thin film are not good.